The invention relates to a control information transmission apparatus for transmitting control information required for data transmission in time division multiplex communication systems.
An apparatus which transmits such control information efficiently is disclosed in the prior art Japanese laid-open patent publication No. 58-34634.
FIG. 7 is a block diagram of the conventional control information insertion and extraction circuit used in such time division multiplex communication systems. In FIG. 7, 51 is a central processing unit (CPU) for controlling the control information transmission apparatus. 52 is a serial interface for transmitting the control information. 53 is an inserting portion for inserting the transmitting control information. 54 is a sending side data transmission line for transmitting the data. 55 is a receiving side data transmission line for receiving the data. 56 is an extracting portion for extracting the received control information. 57 is a serial interface for receiving the control information.
The operation of the conventional control information transmission apparatus is explained hereinafter. The CPU 51 controls the transmitting and received control information. The transmitting control information is outputted from the CPU 51 to the sending side data transmission line 54 through the serial interface 52 and the inserting portion 53. The control information received from the receiving side data transmission line 55 is extracted by the extracting portion 56 and outputted to the CPU 51 through the serial interface 57.
FIG. 8 shows a frame format construction of the Y interface primary group. The transmitting and receiving control information are allocated to the fixed time-slot which is called service channel. 58 is a frame having 24 channels. 59 is the head channel (CH 1) of the frame. 60 is the frame construction of CH 1 having 8 bits in the channel.
61 is a fixed time-slot in which a service channel is allocated in each channel 59 of the frame 58. CPU 51 extracts the control information from the fixed channel in the data signal received from the receiving side data transmission line 55, or inserts the control signal to be transmitted into the service channel and transmits it to the sending side data transmission line 54.
Since the conventional control information insertion and extraction circuit is constructed as described above in the time division multiplex communication systems, there are problems caused by the fact that the transmission rate of the transmitting or receiving control information is fixed. Also, since the time-slot where the control information is inserted is restricted, it is difficult to transmit a lot of control information during a short time.
Therefore, since the conventional system allocates the fixed channel for transmitting the control information, if a system requires the transmission of a lot of control information during a short time, the user area decreases and the system transmission efficiency also decreases.
It is a primary object of the present invention to provide a control information transmission apparatus for use in time division multiplex communication systems for transmitting a lot of control information at a high speed during a short time, and for realizing a high efficiency transmission by decreasing loss of the main data transmitted by the user area of the frame channel.
It is another object of the present invention to provide a control information transmission apparatus for use in time division multiplex communication systems for transmitting a lot of remote loop back information or route changing system data at a high speed during a short time, and for realizing a high efficiency transmission by decreasing loss of the main data transmitted by the user area of the frame channel and also for changing the route at a high speed in order to respond to a system fault.